HD 25 Carb percolting

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FrankR
Posts: 3766
Joined: Tue Mar 10, 2015 6:32 pm
Location: Florida

Re: HD 25 Carb percolting

Postby FrankR » Wed Aug 01, 2018 8:05 pm

Soaking that rotor in oil may not have been the wisest thing to do. Oil makes them swell up. Other than that, I don't know what the problem is with yours.

Shane.R13
Posts: 146
Joined: Tue Jan 30, 2018 10:03 pm

Re: HD 25 Carb percolting

Postby Shane.R13 » Wed Aug 01, 2018 8:19 pm

I'm having the same issue, everything seems in order except my rotor looks swollen to the eye. Ordering a new one from Brian Tomorrow. Hope I have better luck.
Attachments
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1946-49 Johnson TD-20 5HP
1946-51 Johnson HD-25 2.5HP
1959 Evinrude 18hp Golden Jubilee
1978 Artic Spirit(Suzuki) 20HP
1975 Evinrude Mate 2HP
1977 Johnson 25HP
1980 Mercury 18HP
1987 Mariner 9.9HP

and growing hopefully

Chacha53
Posts: 30
Joined: Thu Aug 17, 2017 5:14 am

Re: HD 25 Carb percolting

Postby Chacha53 » Wed Aug 01, 2018 9:52 pm

I soaked it in mineral oil in order to swell it in hopes the cam would fi tighter without any gaps.
My water pick up looks like the rubber has been trimmed off even with the copper tube. It looks blocked in this picture.
I’d be interested in knowing if yours works with a new pump.
Chattanooga, TN

Shane.R13
Posts: 146
Joined: Tue Jan 30, 2018 10:03 pm

Re: HD 25 Carb percolting

Postby Shane.R13 » Wed Aug 01, 2018 11:10 pm

I have trimmed that piece of rubber at the end that looked rough. Hope it does not have an adverse effect. I'll find out I guess. Should the pump be a tight fit on the outer rim as well as around the cam? Or just on the cam and loose on the outer area?
1946-49 Johnson TD-20 5HP
1946-51 Johnson HD-25 2.5HP
1959 Evinrude 18hp Golden Jubilee
1978 Artic Spirit(Suzuki) 20HP
1975 Evinrude Mate 2HP
1977 Johnson 25HP
1980 Mercury 18HP
1987 Mariner 9.9HP

and growing hopefully

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Garry in Tampa
Posts: 2861
Joined: Mon Mar 09, 2015 2:32 pm
Location: Florida

Re: HD 25 Carb percolting

Postby Garry in Tampa » Thu Aug 02, 2018 12:19 pm

ABSOLUTELY NOT ! - It should be a tight fit on the center eccentric cam only. The gap on the outside is for the water. No gap, no water. . . 8-)
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Living my dream because Reality is too expensive . . .

Chacha53
Posts: 30
Joined: Thu Aug 17, 2017 5:14 am

Re: HD 25 Carb percolting

Postby Chacha53 » Thu Aug 02, 2018 4:16 pm

I think trimming is a mistake. I did that to mine and now I can't' get more than a trickle. I found the HD25 parts list and there is a seal listed for the lower end of the water tube. I think that is what I trimmed off. Not sure what to do now. Maybe I could build a seal using black RTV to look like yours.
image.jpeg
You can see the gap on this new pump at 11 o'clock. Too much??
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image.jpeg
You can see the gap on this new pump at 11 o'clock. Too much??
image.jpeg (65.35 KiB) Viewed 240 times
image.jpg
This is mine after I trimmed it.
image.jpg (55.69 KiB) Viewed 240 times
Attachments
image.jpg
Original pump. No gap
image.jpg (55.74 KiB) Viewed 240 times
Chattanooga, TN

aquasonic
Posts: 329
Joined: Tue Mar 10, 2015 7:13 pm
Location: Narragansett, Rhode Island

Re: HD 25 Carb percolting

Postby aquasonic » Fri Aug 03, 2018 5:57 pm

In my experience, even when set up correctly, the HD-25 is a very hot running motor. The integral exhaust/intake/carburetor design is prone to overheating the fuel in the carburetor. Once the carburetor/exhaust/intake get too hot, the fuel can and will boil in the carburetor making it impossible to start the motor until it cools down enough to run again. They can, however, be serviceable motors.

Remember that these motors are around 70 years old, and that means that the water pump AND the water tube seal should be replaced. I own a 1947 HD-25 that cooled fine the first time I ran it, then overheated quickly the next time it ran. After giving me fits, it turned out that the water tube seal/grommet had swelled up from exposure to water. The tiny, maybe 3/16" opening, was closed up significantly, choking off the water supply causing overheating.

Back to the original post, there is a gasket between the gearcase and the midsection that separates water from the gear oil. If you separate the two, then you really need to reseal that gasket, or better yet buy or make one. That is a very important gasket.

Here is a picture of the water tube seal/grommet:
0300582 HD-25 Water Tube Seal.jpg
0300582 HD-25 Water Tube Seal.jpg (1.82 KiB) Viewed 225 times

Chacha53
Posts: 30
Joined: Thu Aug 17, 2017 5:14 am

Re: HD 25 Carb percolting

Postby Chacha53 » Mon Aug 06, 2018 11:24 am

Great info! Where can I get a replacement grommet?
Chattanooga, TN

Shane.R13
Posts: 146
Joined: Tue Jan 30, 2018 10:03 pm

Re: HD 25 Carb percolting

Postby Shane.R13 » Tue Aug 07, 2018 7:04 pm

Garry in Tampa wrote:ABSOLUTELY NOT ! - It should be a tight fit on the center eccentric cam only. The gap on the outside is for the water. No gap, no water. . . 8-)
Image
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Thanks for the diagram Garry. I'll be sure to refer to it when my new pump rotor comes in.
1946-49 Johnson TD-20 5HP
1946-51 Johnson HD-25 2.5HP
1959 Evinrude 18hp Golden Jubilee
1978 Artic Spirit(Suzuki) 20HP
1975 Evinrude Mate 2HP
1977 Johnson 25HP
1980 Mercury 18HP
1987 Mariner 9.9HP

and growing hopefully

aquasonic
Posts: 329
Joined: Tue Mar 10, 2015 7:13 pm
Location: Narragansett, Rhode Island

Re: HD 25 Carb percolting

Postby aquasonic » Tue Aug 07, 2018 7:30 pm

Chacha53 wrote:Great info! Where can I get a replacement grommet?

Best to post an add on our Free Classifieds Section of this website. Members have parts to sell. If no luck, then you can "pay up" for the part.

http://www.marineengine.com/newparts/pa ... OMC0300582

https://www.ebay.com/itm/OMC-EVINRUDE-J ... itleDesc=0


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